1. Field of the Invention
This invention pertains to processes for the preparation of 1H-imidazo[4,5-c]quinolines. More particularly, this invention pertains to processes for the preparation of 1-substituted,4-substituted-1H-imidazo-[4,5-c]quinolines. In another aspect, this invention pertains to intermediates in the preparation of 1H-imidazo[4,5-c]quinolines, and to processes for the preparation of such intermediates.
2. Description of the Related Art
The synthesis of 4-substituted 1H-imidazo[4,5-c]quinolines via 4-chloro-1H-imidazo[4,5-c]quinolines has been reported in U.S. Pat. Nos. 4,689,338 and 4,698,348 (Gerster). The synthetic scheme used therein involves first condensing a quinoline with amine functionality at the 3- and 4-position with a trialkyl orthoester or a functional equivalent thereof to form the 1H-imidazo[4,5-c]quinoline ring system, followed by introduction of a 4-chloro substituent by oxidizing the 5-nitrogen and reacting the resulting N-oxide with a chlorinating agent. Replacement of the 4-chloro substituent with a selected nucleophile such as ammonia then affords the desired 4-substituted-1H-imidazo[4,5-c]quinoline, e.g., the corresponding 1H-imidazo[4,5-c]quinolin-4-amine when ammonia is employed as the nucleophile.